package meng.asymmetric;

import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

import org.apache.commons.codec.binary.Base64;

/**
 * RSA -- 基于因子分解
 * 
 * @author mengzhang6
 *
 */
public class RSADemo {

	public static void jsdRSA(String str) {
		try {
			// 初始化密钥
			KeyPairGenerator keyPairGenerator = KeyPairGenerator
					.getInstance("RSA");
			keyPairGenerator.initialize(512);
			;
			KeyPair keyPair = keyPairGenerator.generateKeyPair();
			RSAPublicKey rsaPublicKey = (RSAPublicKey) keyPair.getPublic();
			RSAPrivateKey rsaPrivateKey = (RSAPrivateKey) keyPair.getPrivate();
			System.out.println("公钥：\n"
					+ Base64.encodeBase64String(rsaPublicKey.getEncoded()));
			System.out.println("私钥：\n"
					+ Base64.encodeBase64String(rsaPrivateKey.getEncoded()));
			System.out.println("---------------------");

			// 私钥加密 公钥解密---加密
			PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(
					rsaPrivateKey.getEncoded());
			KeyFactory keyFactory = KeyFactory.getInstance("RSA");
			PrivateKey privateKey = keyFactory
					.generatePrivate(pkcs8EncodedKeySpec);
			Cipher cipher = Cipher.getInstance("RSA");
			cipher.init(Cipher.ENCRYPT_MODE, privateKey);
			byte[] result = cipher.doFinal(str.getBytes());
			System.out.println("私钥加密 公钥解密---加密:");
			System.out.println(Base64.encodeBase64String(result));

			// 私钥加密 公钥解密---解密
			X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(
					rsaPublicKey.getEncoded());
			keyFactory = KeyFactory.getInstance("RSA");
			PublicKey publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
			cipher.init(Cipher.DECRYPT_MODE, publicKey);
			result = cipher.doFinal(result);
			System.out.println("私钥加密 公钥解密---解密:");
			System.out.println(new String(result));
			System.out.println("---------------------");

			// 公钥加密 私钥解密---加密
			x509EncodedKeySpec = new X509EncodedKeySpec(
					rsaPublicKey.getEncoded());
			keyFactory = KeyFactory.getInstance("RSA");
			publicKey = keyFactory.generatePublic(x509EncodedKeySpec);
			cipher.init(Cipher.ENCRYPT_MODE, publicKey);
			result = cipher.doFinal(str.getBytes());
			System.out.println("公钥加密 私钥解密---加密:");
			System.out.println(Base64.encodeBase64String(result));

			// 公钥加密 私钥解密---解密
			pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(
					rsaPrivateKey.getEncoded());
			keyFactory = KeyFactory.getInstance("RSA");
			privateKey = keyFactory.generatePrivate(pkcs8EncodedKeySpec);
			cipher = Cipher.getInstance("RSA");
			cipher.init(Cipher.DECRYPT_MODE, privateKey);
			result = cipher.doFinal(result);
			System.out.println("公钥加密 私钥解密---解密:");
			System.out.println(new String(result));

		} catch (Exception e) {
			e.printStackTrace();
		}
	}

}
